Are power stations wasting energy during Earth Hour?

[chebyshevF]

Has everyone heard about the Earth Hour movement? Where you're encouraged to turn off anything that uses electricity in your home, for an hour, to conserve energy.

What I'm wonedering is: let's say that a large group of people depend on a specific power station, so when they all, or the majority, turn off all electrical appliances, what happens with the power that is generated at the power station? I'm guessing they still continue to generate electricity, and isn't it true that this power cannot be stored, so would it be right to say that the power stations are generating electricity that is just being wasted? Since for that whole hour, there wouldn't be as much of a demand, therefore the power station is pointlessly generating electricity that nobody is using for the time being?

I'm not sure if I make sense, but basically: is the power that is generated at the power station, being wasted owing to the fact that it isn't being used during the hour period?

 

[vk6kro]

The generators at the power station become easier to turn if the load is reduced.

So, the power plant which turns the generators uses less fuel to rotate the generators at the right speed.

No unwanted power is produced and less fuel is used.

As long as the power station keeps producing the right voltage, the current drawn just depends on which appliances are switched on or off.

 

[chebyshevF]

So the rate at which the generators are being turned depends on how high the demand is at the load?

But how does the power station know when the demand is high or low? Wouldn't it take some amount of time for the power station to be given some form of feed back by the load, that more power is needed, therefore they need fuel?

 

[vk6kro]

So the rate at which the generators are being turned depends on how high the demand is at the load?

But how does the power station know when the demand is high or low? Wouldn't it take some amount of time for the power station to be given some form of feed back by the load, that more power is needed, therefore they need fuel?

The speed of the generator rotation determines the frequency of the output. This may be 50 or 60 Hz but it must remain constant regardless of load.

If this starts to decrease, automatic sensors detect the difference and apply slightly more accellerator pressure to bring the speed back to normal again.
If everyone in a whole city turned off the power at once, the power station might have a few seconds of rapid adjustment while the power from the power plant was reduced.

These are very large heavy machines, so minor changes in current drain have little effect on the speed of their rotation.

The current drawn is also measured from second to second and the mechanical power input is adjusted automatically to maintain constant RPM from the generators.

 

[Drakkith]

So if you have a generator with practically zero load and another one at near max load, both turning at the same RPM, then the one with zero load will use less fuel?

 

[sophiecentaur]

Yes. It's like a couple riding a tandem. The one at the back can just pedal lightly and the guy in front would just think the hill was steeper than it looked.

Nuclear Power Stations are more of a problem because (see recent news) they take a long time to shut down completely so they produce no steam.